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- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 356 1950-55
- Porsche 356A 1955-59
- Porsche 356B 1959-63
- Porsche 356C 1963-65
Rennline Carbon Fiber Velocity Stacks (50mm Tall) |
Precision Airflow & Top-End Power for cars with Carburettors
Sold individually
The Rennline Carbon Fiber Velocity Stacks (50mm tall)
are designed to optimise intake airflow and engine performance in high-revving
applications. Constructed from ultra-lightweight carbon fibre, these 2"
(50mm) stacks enhance air velocity and resonance, allowing for improved
pressure pulse frequencies and more efficient airflow through the intake
system.
Fits:
Compared to a 2.25" trumpet, these velocity stacks deliver superior high-RPM torque and throttle response, making them ideal for motorsport and performance-focused Porsche builds. With a standard 65mm mounting hole pattern, they’re designed for easy installation on a wide range of custom and carburettor-based setups.
Each velocity stack is sold individually and built to withstand the heat, vibration, and stress of competitive driving — offering both technical performance and sleek carbon aesthetics.
What Do Velocity Stacks Do?
Velocity stacks (also known as intake trumpets) are
engineered to improve the airflow into the engine’s intake system, smoothing
the transition of air and increasing volumetric efficiency.
Core Functions:
- Increase air velocity into the throttle body or carburettor.
- Improve top-end horsepower and torque output.
- Optimise pressure waves for enhanced combustion efficiency.
- Smooth airflow and reduce turbulence at the intake mouth.
- Deliver sharper throttle response at high RPM.
In short, they allow your engine to breathe more efficiently, resulting in better performance, faster throttle response, and improved sound.
Why Do Velocity Stacks Fail or Need Replacement?
Over time, velocity stacks — particularly older aluminium or plastic types — can degrade due to heat cycling, vibration, and exposure to contaminants.
Common Causes of Failure Include:
- Cracking or delamination from extreme heat and vibration.
- Corrosion or fatigue in metal-based versions.
- Airflow restriction caused by dirt or damage.
- Poor fitment leading to air leaks or misalignment.
- Material fatigue from repeated stress during performance driving.
When velocity stacks weaken or distort, airflow becomes uneven — reducing efficiency and potentially causing imbalanced fuel-air ratios or power loss.
Why Upgrade to Rennline Carbon Fiber Velocity Stacks?
Upgrading to Rennline’s carbon fibre design provides enhanced durability, lower weight, and optimal airflow characteristics — ideal for performance-focused engines and track cars.
Key Benefits:
- Increases torque and top-end power at high RPMs.
- Lightweight carbon construction for reduced mass and improved airflow.
- Precision 50mm height ideal for performance tuning.
- Improved pressure pulse frequency for enhanced throttle response.
- Direct-fit design with 65mm mounting holes.
- Sleek carbon fibre finish adds a professional motorsport aesthetic.
Rennline’s carbon fibre stacks combine engineering precision with performance-driven design — perfect for those seeking peak airflow efficiency and style.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
M91
The product you are viewing cross references to these numbers
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
This Product Fits:
Porsche 911 with carbs
K&N brand air filter, part number 56-1240 which is now 56-1770-1 this is for Weber 40/46 IDA (Triple carb) as fitted to Porsche 911.
K&N Custom Air Filter kits are designed to allow the maximum performance from your carburettors, yet keep the dirt on the outside where it belongs. These assemblies come with top and base plates and the famous K&N High-Flow Washable Air Filter.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
56-1770-2
The product you are viewing cross references to these numbers
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
Fits:
Porsche 911 1972-1977
Click 'Zoom in' for large parts diagram.
Diagram ref no 10
Price shown is for each.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
91110816700
The product you are viewing cross references to these numbers
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
Fits:
Porsche 911 1965-89
Product Specifications:
Part Number: E-3671
Product Style: Oval Air Filter
Air Filter Shape: Oval
Height: 3.25 in (83 mm)
Inner Wire: No
Inside Length: 10.75 in (273 mm)
Inside Width: 4 in (102 mm)
Outside Length: 12 in (305 mm)
Outside Width: 5.25 in (133 mm)
Top Style: Open
Top Material/Finish: None
Filter Material: Cotton Gauze
K&N® washable, reusable High-Flow Air Filters™ feature a state-of-the-art design of layered, oiled cotton media engineered to improve airflow and capture contaminants, and are designed to provide an increase in horsepower.
Each performance air filter is reusable, engineered to last for the entire lifespan of your vehicle, and backed by K&N's 10-Year/Million Mile Limited Warranty.
K&N drop-in replacement filters are designed to install easily into your factory air box.
Works with Original Equipment Manufacturer Vehicle Electronics.
Environmentally Friendly, K&N Reusable Air Filters
Upgrade today and start enjoying superior airflow and superior performance from K&N's most popular product!
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
E-3671
The product you are viewing cross references to these numbers